You think it's tough out there on the streets? Try going to the theatre. That was my first reaction upon reading of a homophobic incident the other evening at the West End musical Spamalot. According to a report in whatsonstage.com's discussion room, two men took against a fellow theatregoer they assumed to be gay, calling him "little queer", faggot" and "nonce" and sending him and his male companion fleeing into the relative safety of the night. This particular musical has developed - both on Broadway and, evidently, here as well - a reputation for recognisably blokeish audiences at odds with the women and gay men who make up musical theatre's traditional constituency. But verbal abuse? That's a new one on me. Let' s hope the same perpetrators don't find their way to Tony Kushner's theatrical epic Angels in America, the self-described "gay fantasia" that opens this week at west London's Lyric Hammersmith.

The stalls these days are sometimes more exciting - or, to be exact, excitable - than what is transpiring on stage. In January, I was bemused during a performance of the Russian play A Family Affair at Dalston's Arcola theatre to find myself seated next to a cheerful enough drug dealer who was clearly more interested in scoring a sale than making it through a period farce by Alexander Ostrovsky. Fidgeting for much of the first act, and frequently talking aloud to no one in particular, he at one point turned to ask whether I was bored, since he saw me taking notes (on the production, not on his behaviour). Bored? Not with such diversionary entertainment, which came to an abrupt end when he noisily departed the show mid-performance, leaving behind a female companion who joined him at the interval. Neither one was seen again.

It's in the nature of live events, of course, that the auditorium itself be lively: look at the early tenure of Shakespeare's Globe under Mark Rylance, where audiences were all but coerced into buying out the vegetable section of Sainsbury's so as to have something to hurl at the stage. What interests me is the raised stakes of these recent episodes compared to what has gone before. I remember several decades ago the reports from Broadway's Brooks Atkinson Theatre of the interloper at Michael Frayn's Benefactors who wandered up the aisle on to the stage and started tossing props into the audience while cast members Glenn Close and Sam Waterston looked on aghast. Closer to home was the incident at the old Hampstead Theatre in 1986 during a performance of the play Circle and Bravo when star Faye Dunaway was confronted mid-show by a fan who announced that he had come to whisk her away: cue the immediate hiring of bodyguards to safeguard the visiting screen siren.

Amid such events, the usual theatrical indiscretions seem comparatively benign. How could I be aggrieved, during a Broadway performance in May of the August Wilson play Radio Golf, with the man next to me, who sent and retrieved messages on his Blackberry during the entire performance? He stayed till the end and cheered heartily, though perhaps that was because the show had finished. That same week, the man behind me at Talk Radio only turned off his own portable radio (a case of over-empathy with the play's title?) when the noise was brought to his attention. Drug dealers and bullies, though, are something new, or so it would seem. Perhaps others have their own stories to share, in which case forewarned is forearmed - that is, until theatregoers start bearing arms.